The present invention generally relates to disc drive systems and, more particularly, to apparatus and techniques for cooling disc drive systems.
Disc drive systems are configured as stand-alone devices, with plug-in communications to computer systems, or as integral sub-systems within a computer system, such as in a personal computer or server. As disc drive systems become faster and more powerful, they consume increasingly greater quantities of power. This power is dissipated primarily as operating heat. As a result, the amount of internally-generated operating heat has correspondingly increased to the extent that an adequate heat removal strategy has become a major design concern in these more powerful disc drive devices. With the advent of high RPM drives, such as 10K RAM drives, and high mass storage requirements, cooling requirements for disc drive systems has surpassed the capacity of known thermal conduction techniques.
In a conventional disc drive system, discs of recording media are fitted onto a spindle. The discs and spindle rotate by a motor at high speed on bearings disposed within a base housing. The friction generated between the spindle bearing and the base housing is a principal source of heat generated during disc drive system operation. The spindle motor, also typically disposed in the base housing, is another significant heat source. Excess heat can damage disc drive components thereby shortening their lives. Inadequate heat conduction by the mass of the base housing, away from the heat-generating components (e.g., spindle motor and bearing), can result in isolated xe2x80x9chot spotsxe2x80x9d and undesirably high component temperature adversely affecting the disc drive system""s operation, reliability and longevity.
Typically, operating heat from the spindle bearing and motor are conducted through the mass of the base housing and dissipated to ambient. The quantity of heat conducted away from the heat-generating components is a function of the temperature differential between the heat-generating components and the base housing, the thermal conductivity of the base housing mass from near the heat-generating components to the base housing surface exposed to ambient, and the temperature differential between the base housing surface and ambient.
Common conventional approaches for improving disc drive cooling are directed at increasing the quantity of heat transferred from the base housing surfaces to ambient by improving the temperature differential between the base housing surface and ambient. In particular, one favored approach uses mechanical means (e.g., fans) to force air flow past the base housing to replace hot air with cooler air, thereby reducing ambient air temperature near the base housing surface and increasing the temperature differential. Other conventional approaches are directed at increasing the base housing heat-dissipating surface area (e.g., adding finned heat sink configurations). Conventional cooling approaches, such as fans and heat sinks, add volume to the disc drive system package and increase costs. Mechanical cooling means require additional energy, generate additional heat (which must also be dissipated), and make noise. Mechanical fans are also subject to failure.
It will be appreciated that there is a need for a maintenance-free system and method for effectively cooling disc drive components without adding volume, additional heat, or significant cost. A disc drive system and method that address the aforementioned problems, as well as other related problems, are therefore desirable.
According to one aspect of the present invention, there is provided a disc drive system and a method for removing heat away from near disc drive components by using an internal working fluid to more efficiently transport the heat. The disc drive system includes a rotating disc storage device having at least one heat-generating component, and a base housing internally having a sealed heat transport structure containing a working fluid. The rotating disc storage device is disposed on the base housing. The heat-generating component(s) of the disc storage device are in a heat exchange relationship with the base housing.
The sealed heat transport structure is adapted to receive heat from a first portion of the base housing, fluidly transport the heat to a second portion of the base housing, and release the heat to the second portion of the base housing. The working fluid absorbs heat from near the first portion of the base housing. Working fluid in a gas phase transports the heat, by thermal expansion, to near the second portion of the base housing where the working fluid condenses into a liquid form and releases the heat. The liquid form of the working fluid flows by gravity and/or is drawn by capillary action back near the first portion of the base housing in a continuous cycle. The heat transport structure is optionally inclined to assist gravity flow of liquid working fluid and internally adapted to have a wicking surface, or contain a wicking structure, to facilitate the capillary action.
According to another aspect of the present invention, there is provided a method for making a disc drive of the present invention. The heat transport structure is formed by drilling, casting or embedding fluid passages in the base housing, partially filling the fluid passages with the working fluid, and sealing the fluid passages to retain the working fluid. Prior to sealing, the fluid passages are optionally evacuated to reduce internal pressure, thereby lowering the boiling point of the working fluid contained therein.